'\" te
.\"  Copyright (c) 2001, Sun Microsystems, Inc.  All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH KVM_OPEN 3KVM "May 2, 2002"
.SH NAME
kvm_open, kvm_close \- specify a kernel to examine
.SH SYNOPSIS
.LP
.nf
\fBcc\fR [ \fIflag\fR\&.\|.\|. ] \fIfile\fR\&.\|.\|. \fB-lkvm\fR [ \fIlibrary\fR\&.\|.\|.]
#include <kvm.h>
#include <fcntl.h>

\fBkvm_t *\fR\fBkvm_open\fR(\fBchar *\fR\fInamelist\fR, \fBchar *\fR\fIcorefile\fR, \fBchar *\fR\fIswapfile\fR, \fBint\fR \fIflag\fR,
     \fBchar *\fR\fIerrstr\fR);
.fi

.LP
.nf
\fBint\fR \fBkvm_close\fR(\fBkvm_t *\fR\fIkd\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBkvm_open()\fR function initializes a set of file descriptors to be used
in subsequent calls to kernel virtual memory ( VM) routines.  It returns a
pointer to a kernel identifier that must be used as the \fIkd\fR argument in
subsequent kernel VM function calls.
.sp
.LP
The \fInamelist\fR argument specifies an unstripped executable file whose
symbol table will be used to locate various offsets in \fIcorefile\fR. If
\fInamelist\fR is \fINULL\fR, the symbol table of the currently running kernel
is used to determine offsets in the core image.  In this case, it is up to the
implementation to select an appropriate way to resolve symbolic references, for
instance, using \fB/dev/ksyms\fR as a default \fInamelist\fR file.
.sp
.LP
The \fIcorefile\fR argument specifies a file that contains an image of physical
memory, for instance, a kernel crash dump file (see \fBsavecore\fR(8)) or the
special device \fB/dev/mem\fR. If \fIcorefile\fR is \fINULL\fR, the currently
running kernel is accessed, using \fB/dev/mem\fR and \fB/dev/kmem\fR.
.sp
.LP
The \fIswapfile\fR argument specifies a file that represents the swap device.
If both \fIcorefile\fR and \fIswapfile\fR are \fINULL\fR, the swap device of
the currently running kernel is accessed.  Otherwise, if \fIswapfile\fR is
\fINULL\fR, \fBkvm_open()\fR may succeed but subsequent \fBkvm_getu\fR(3KVM)
function calls may fail if the desired information is swapped out.
.sp
.LP
The \fIflag\fR function is used to specify read or write access for
\fIcorefile\fR and may have one of the following values:
.sp
.ne 2
.na
\fB\fBO_RDONLY\fR\fR
.ad
.RS 12n
open for reading
.RE

.sp
.ne 2
.na
\fB\fBO_RDWR\fR\fR
.ad
.RS 12n
open for reading and writing
.RE

.sp
.LP
The \fIerrstr\fR argument is used to control error reporting.  If it is a null
pointer, no error messages will be printed. If it is non-null, it is assumed to
be the address of a string that will be used to prefix error messages generated
by \fBkvm_open\fR. Errors are printed to \fBstderr\fR. A useful value to supply
for \fIerrstr\fR would be \fIargv\fR[0]. This has the effect of printing the
process name in front of any error messages.
.sp
.LP
Applications using  \fBlibkvm\fR are dependent on the underlying data model of
the kernel image, that is, whether it is a 32\(mibit or 64\(mibit kernel.
.sp
.LP
The data model of these applications must match the data model of the kernel in
order to correctly interpret the size and offsets of kernel data structures.
For example, a 32\(mibit application that uses the 32\(mibit version of the
\fBlibkvm\fR interfaces will fail to open a 64\(mibit kernel image.  Similarly,
a 64\(mibit application that uses the 64\(mibit version of the \fBlibkvm\fR
interfaces will fail to open a 32\(mibit kernel image.
.sp
.LP
The \fBkvm_close()\fR function closes all file descriptors that were associated
with \fIkd\fR. These files are also closed on \fBexit\fR(2) and
\fBexecve\fR(\|) (see \fBexec\fR(2)). \fBkvm_close()\fR also resets the
\fBproc\fR pointer associated with \fBkvm_nextproc\fR(3KVM) and flushes any
cached kernel data.
.SH RETURN VALUES
.sp
.LP
The \fBkvm_open()\fR function returns a non-null value suitable for use with
subsequent kernel VM function calls. On failure, it returns \fINULL\fR and no
files are opened.
.sp
.LP
The \fBkvm_close()\fR function returns 0 on success and \(mi1 on failure.
.SH FILES
.sp
.ne 2
.na
\fB\fB/dev/kmem\fR\fR
.ad
.RS 14n

.RE

.sp
.ne 2
.na
\fB\fB/dev/ksyms\fR\fR
.ad
.RS 14n

.RE

.sp
.ne 2
.na
\fB\fB/dev/mem\fR\fR
.ad
.RS 14n

.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Stable
_
MT-Level	Unsafe
.TE

.SH SEE ALSO
.sp
.LP
.BR exec (2),
.BR exit (2),
.BR pathconf (2),
.BR getloadavg (3C),
.BR sysconf (3C),
.BR kstat (3KSTAT),
.BR kvm_getu (3KVM),
.BR kvm_kread (3KVM),
.BR kvm_nextproc (3KVM),
.BR kvm_nlist (3KVM),
.BR libkvm (3LIB),
.BR proc (5),
.BR attributes (7),
.BR lfcompile (7),
.BR savecore (8)
.SH NOTES
.sp
.LP
Kernel core dumps should be examined on the platform on which they were
created. While a 32-bit application running on a 64-bit kernel can examine a
32-bit core dump, a 64-bit application running on a 64-bit kernel cannot
examine a kernel core dump from the 32-bit system.
.sp
.LP
On 32-bit systems, applications that use \fBlibkvm\fR to access the running
kernel must be 32-bit applications. On systems that support both 32-bit and
64-bit applications, applications that use the \fBlibkvm\fR interfaces to
access the running kernel must themselves be 64-bit applications.
.sp
.LP
Although the \fBlibkvm\fR API is Stable, the symbol names and data values that
can be accessed through this set of interfaces are Private and are subject to
ongoing change.
.sp
.LP
Applications using  \fBlibkvm\fR are likely to be platform- and
release-dependent.
.sp
.LP
Most of the traditional uses of \fBlibkvm\fR have been superseded by more
stable interfaces that allow the same information to be extracted more
efficiently, yet  independent of the kernel data model.  For examples, see
\fBsysconf\fR(3C), \fBproc\fR(5), \fBkstat\fR(3KSTAT), \fBgetloadavg\fR(3C),
and \fBpathconf\fR(2).
